Only if you changed the actual filename also LOL
The fixfilenames function take a file like this
image test.jpg
and makes it
image_test.php
I do not see how it would work fine simply because if your file on disk is image test.jpg just changing the name in the photos table to image_test.jpg would break the image and when you rebuild thumbs etc it will delete the image.
See what I am saying. fixfilenames alters file itself to whatever name and that name is stored in the bigimage field in the photos table. You can not change a name in the database without actually changing the physical file on disk.